a lot of the pics where you see tons off people at the sandbar aren't totally accurate.
If you go with a group tour then it can be like that, but if you are vacationing with several people you can actually charter a boat to take you out there (its actually sometimes a lot cheaper then the group rates) and the experience is really awesome. It is a lot different feel than the dive though, lots of alcohol and the eventual stop at rum points makes it a good deal of fun.
That being said standing on the sand having them throw a stingray on your back is very different from having them swim all around you, even though you are just 12ish feet deep its a very cool and unique experience and if I had to pick between the two I'd have to pick the dive.
Although you do have the option of doing a snorkel trip to SRC and then diving eagle ray pass - you will see groups of eagle rays, but not in the proximity that you would see them at the SRC dive.
TLDR version: you can't really go wrong